Cobalt bearing hardfacing alloys are used to protect wear surfaces in industrial applications. Stellite, a product of Stoody Deloro, is the most common cobalt based alloy in current use, but it is very expensive and is not machinable by normal methods and procedures. Cobalt bearing surface alloys have good resistance to galling and to cavitation erosion, reasonably good resistance to abrasion and corrosion, and good weldability by plasma-transferredarc, gas-tungsten-arc, and gas-metal-arc welding, the processes most commonly used to apply these alloys. They are used for hardfacing to provide wear resistant surfaces. They are also used to protect wear surfaces in nuclear power plants; however, they are the source of close to 80 percent of all radiation exposure suffered by plant maintenance workers.
Further information concerning cobalt based alloys is set forth in an article entitled "The Search for Cobalt-Free Hardfacing Alloys" appearing in Welding Design Fabrication, July, 1989, pp. 46-49, which discusses cobalt free surfacing alloys.
The preferred method of hardfacing a surface with an alloy utilizes the bulkweld process of alloy powder and a wire or electrode melted together in a welding arc and simultaneously welded to a base plate or a component while melting an amount of the surface thereof to obtain a weld bond, such as set forth in U.S. Pat. No. 3,076,888. Other patents illustrating hardfacing are U.S. Pat. Nos. 3,000,094; 3,060,307; 3,062,948; 3,407,478; 3,494,749; 3,513,288; 3,517,156; 3,588,432; and 3,609,292.
It would be highly advantageous to provide a hardfacing alloy having a substantially reduced cobalt content than those in common use today, which is substantially less expensive over the more common cobalt based alloys; that is, an alloy which is about one-half to one-third the cost of other alloys having a cobalt base, and one which lends itself to being machined by standard tooling and equipment which is not possible with current cobalt based alloys in common use because they contain primary carbides. The alloy of the present invention does not develop primary carbides.